An engine block may be designed to include a coating, e.g., a ferrous material, coated on the inner surface of the cylinder bore. Such a coating may allow engine designs having reduced overall weight of the engine block and enhanced abrasion resistant properties for inner surfaces of the cylinder bores. For example, a coating may be particularly useful for aluminum engine blocks.
It is desirable to prevent a coating from adhering to a lower portion of an adjacent cylinder bore. For example, if while spraying a coating on one cylinder bore, some amount of spray is directed to an adjacent cylinder bore, the spray in the adjacent cylinder bore will have a lower degree of adhesion. Thereafter, if the adjacent cylinder bore is coated, the coating in that cylinder bore will continue to have a low degree of adhesion to the cylinder bore. This may cause the coating in that cylinder bore to break free during engine operation, which may lead to poor engine performance or even engine failure.
One method to prevent a coating from adhering to a lower portion of the adjacent cylinder bore requires covering lower parts of the cylinder bore with a masking shield prior to spraying the cylinder bore with a coating. The masking shield protects the lower portion of the cylinder bore when the coating is formed on the inner surface of the engine cylinder bore. After spraying, the masking shield must be removed.
Removing masking shields is labor-intensive. Further, masking shields are consumable items that contribute to engine manufacturing expenses. In addition, since a coating may have formed a continuous layer connecting an inner surface of a cylinder bore to a masking shield, removal of a masking shield runs the risk of breaking and damaging the coating formed on the inner surface of the cylinder bore.